as i am not level 30 my build will not have any mastery or rune but im sure that if you played lol a lot you'l know what to take and if not and looking for a good build (below level 20 not much have got great mastery and runes....thats what friend of mine who played a lot told me (over 500 win))....
p.s. sorry for grammar or other mistakes....also this is the first of my build so i havent understood all the thing i can do with that site (images, mastery tree, skill sequence etc) i'll edit my build when i'l know how to do that

all of my build have been tested by me or some friend against real player and have made their proof, all will be explained and after reading this guide you should play this hero quite well

this build will show you a single way to play a great tank/off-tank singed

first item: sapphire crystal as it give you mana and health( due to singed passive) to this add mana and life potion to stay in your line a little longer and harass with your poison
second item: boots of speed (u can buy one or 2 potion if u think it can help)
third: upgrade sapphire crystal into tear of the goddess to gain mana (and life by the way)and mana regen
fourth:finish youre boots with mercury treads and start building a rod of ages beginning by sapphire crystal/catalyst the protector
fifth: finish rod of ages(wich will give you ton of mana life and ability power) asap then start rylai crystal scepter (more life, great ability power and best of all....on-it slow effect for all of your attack include the poison)
sixth: finish rylais and go for nothing more than a rabadons deathcap ( tons of damage due to ability power)
7: you can exchange the order you will build 6 and 7 if you think you need to be a little more tanky or if you think your damage output is great for the game advancement, seventh item is gardian angelyou can also take aegis of the legion if you want to be more support for your team and if you know that you wont die

and last but not least is the upgrade of your tear of the goddess: archangels staff

with those items your poison will be doing 70+(near 180) damage per second and your fling 300+( near 425) damage wich is really great
also this build wont cost you a lot ( between 16,7 and 17k depending on potion/ and ward you might have bought) and be easy to get as singed is great to farm/jungle (you can do dragon solo by the time you get rabadon and if you use your ult to get spell vamp)and with 2 or 3 kills this late game build can easily be finished before end of game.

at lvl 1 put one point in poison trail, level 2 fling, level 3 mega adhesive vial, then max poison trail as soon as possible as it will be your harrassing/farming attack (dont forget to put point for your ultimate), then max fling( to do more damage you can with it) and the last skill you should be upgrading is the slow thing cause it only slow and doesnt do damage so it will only help you escape dangerous situation or stop an enemy from fleeing but to stop an enemy you got rylais and fling and to escape dangerous situation gost and cleanse (dont forgot to use it...it could save your ***) and poison trail...no-one want to chase singed as he will take over-time damage for nothing

there is some spell that low-level are using but should never get use (im talking about revive and heal) if youre playing smart ignite wont be useful as you get your poison to do over time damage, you wont need clarity cause as soon as you will get your tear of the goddess your mana regen will be so great you will never (really....never)never get out of mana even if youre running with your poison active for all the game duration, fortify can be useful if youre a tank nammed alistair (or some other character that can stun,taunt you close to their turrets to take first blood) otherwise dont even thinkabout it,clairvoyance ...really....have someone really used this? beeing singed? if yes they were having teleport and they were stupid.....teleport...can be useful to prevent gank or to make some but the 300 second cooldown do that i'm never using it. now the spell you can think of taking : ghost : in gank use ghost to past trought unit and lay your poison everywhere or the flee from them (if youre loosing)cleanse is used to flee by easily avoiding cc, flash can be useful to pass trought wall or to teleport in front of a running character to damage him with your poison by running in front of him,rally can help a little if well placed like in gank/teamfight and thats all i think for summonners spell( tell me if i forgot something) (havent talked about smite? well you dont need it to jungle past level 10 and singed isnt a level one jungle because he havent got spellvamp/lifesteal))

easiest **** ever: press q then run into the enemy you want to dammage and turn around till it die(if its a champion) or until he have lost half of is health...samething to jungle except that you can use fling to damage lizard elder and golem faster than with only your poison....you can also do dragon solo by activating your ultimate but watch out to avoid gank as ward will often be placed at baron and dragon cause they are valuable

run into team fight with your poison activated, fling out the one you want your team to kill easily or fling in(for the same reason) watch out who you will fling and were as amumu, and galio got devastating AoE ultimate, amumu does also deal massive damage as he hit % of live per second with despair, garen is also dangerous to fling in due to his «spin to the death» also udyr as he can stun every single one of you for one second, alistair because he can tank you all(and he surely know it) there might be other i forgot but this is it for who to/not to fling, the adhesive vial should be used to cut the path of fleeing ennemy(shout in front of them not on them) or to prevent them from helping their ally by slowing them(75% + your rylais 15% does almost make them unable to move) your ultimate can be used to: run faster, do greater dammage, gain health when farming with your poison and dont fear to use it, its only 70 second cooldown and it last 25 second wich is really really long for an over-time ultimate

i hope you have read (and understood) every thing), enjoy playing singed as he is really annoying to face and kinda hard to kill